Psoriasis Flashcards
(28 cards)
Psoriasis: Definition
Psoriasis is a common (prevalence around 2%) and chronic inflammatory skin disorder.
It generally presents with red, scaly patches on the skin although it is now recognised that patients with psoriasis are at increased risk of arthritis and cardiovascular disease.
There are 2 peak ages of presentations:
- Type 1 (20s)
- Type 2 (50s)
Psoriasis: Pathophysiology (4)
- Multifactoral
- Genetic
- Immunological
- Enivronmental
Psoriasis: Pathophysiology - MULTIFACTORAL
Multifactorial and not yet fully understood
Psoriasis: Pathophysiology - GENETIC
Associated HLA-B13, -B17, and -Cw6. Strong concordance (70%) in identical twins
Psoriasis: Pathophysiology - IMMUNOLOGICAL
Immunological: abnormal T cell activity stimulates keratinocyte proliferation.
There is increasing evidence this may be mediated by a novel group of T helper cells producing IL-17, designated Th17.
These cells seem to be a third T-effector cell subset in addition to Th1 and Th2
Psoriasis: Pathophysiology - ENVIRONMENTAL
It is recognised that psoriasis may be worsened (e.g. Skin trauma, stress), triggered (e.g. Streptococcal infection) or improved (e.g. Sunlight) by environmental factors
Psoriasis: SUBTYPES (4)
- Plaque psoriasis
- Flexural psoriasis
- Guttate psoriasis
- Pustular psoriasis
Psoriasis: Subtypes - PLAQUE psoriasis
The most common sub-type resulting in the typical well demarcated red, scaly patches affecting the extensor surfaces, sacrum and scalp
Psoriasis: Subtypes - FLEXURAL psoriasis
In contrast to plaque psoriasis the skin is smooth
Psoriasis: Subtypes - GUTTAE psoriasis
Transient psoriatic rash frequently triggered by a streptococcal infection. Multiple red, teardrop lesions appear on the body
Psoriasis: Subtypes - PUSTULAR psoriasis
Commonly occurs on the palms and soles
Psoriasis: Other features (2)
- Nail signs: pitting, onycholysis, subungal kyperkeratosis
- Arthritis
Psoriasis: Complications
- psoriatic arthropathy (around 10%)
- increased incidence of metabolic syndrome
- increased incidence of cardiovascular disease
- increased incidence of venous thromboembolism
- psychological distress
Psoriasis: Triggers
- Stress
- Infections
- Skin trauma
- Drugs: beta blockers, lithium, antimalarials (chloroquine and hydroxychloroquine), NSAIDs and ACE inhibitors, infliximab
- Alcohol
- Obesity
- Smoking
- Climate
Psoriasis: SIGNS
Symmetrical well defined red plaques, with silvery scale on extensor aspects of elbows, knees, scalp and sacrum
Psoriasis: Management of chronic plaque psoriasis
- regular emollients may help to reduce scale loss and reduce pruritus
- FIRST-line: NICE recommend a potent corticosteroid applied once daily plus vitamin D analogue applied once daily (applied separately, one in the morning and the other in the evening) for up to 4 weeks as initial treatment
- SECOND-line: if no improvement after 8 weeks then offer a vitamin D analogue twice daily
- THIRD-line: if no improvement after 8-12 weeks then offer either: a potent corticosteroid applied twice daily for up to 4 weeks or a coal tar preparation applied once or twice daily short-acting dithranol can also be used
Psoriasis: Differential diagnosis
- Eczema
- Tinea
- Mycosis fungiodes
- Seborrhoeic dermatitis
Using topical steroids in psoriasis
- As we know topical corticosteroid therapy may lead to skin atrophy, striae and rebound symptoms
- Systemic side-effects may be seen when potent corticosteroids are used on large areas e.g. > 10% of the body surface area
- NICE recommend that we aim for a 4 week break before starting another course of topical corticosteroids
- They also recommend using potent corticosteroids for no longer than 8 weeks at a time and very potent corticosteroids for no longer than 4 weeks at a time
What should I know about vitamin D analogues?
- Examples of vitamin D analogues include calcipotriol (Dovonex), calcitriol and tacalcitol
- They work by reducing cell division and differentiation
adverse effects are uncommon - Unlike corticosteroids they may be used long-term
- Unlike coal tar and dithranol they do not smell or stain
- They tend to reduce the scale and thickness of plaques but not the erythema
- They should be avoided in pregnancy
- The maximum weekly amount for adults is 100g
STEROIDS in psoriasis
- Topical steroids are commonly used in flexural psoriasis and there is also a role for mild steroids in facial psoriasis. - If steroids are ineffective for these conditions vitamin D analogues or tacrolimus ointment should be used second line
- Patients should have 4 week breaks between course of topical steroids
- Very potent steroids should not be used for longer than 4 weeks at a time.
- Potent steroids can be used for up to 8 weeks at a time
- The scalp, face and flexures are particularly prone to steroid atrophy so topical steroids should not be used for more than 1-2 weeks/month
SCALP psoriasis
- NICE recommend the use of potent topical corticosteroids used once daily for 4 weeks
- If no improvement after 4 weeks then either use a different formulation of the potent corticosteroid (for example, a shampoo or mousse) and/or a topical agents to remove adherent scale (for example, agents containing salicylic acid, emollients and oils) before application of the potent corticosteroid
Face, flexutal and genital psoriasis
NICE recommend offering a mild or moderate potency corticosteroid applied once or twice daily for a maximum of 2 weeks
Psoriasis: Secondary care management (2)
- Phototherapy
- Systemic therapy
Psoriasis: Secondary care management - PHOTOTHERAPY
narrow band ultraviolet B light is now the treatment of choice. If possible this should be given 3 times a week
photochemotherapy is also used - psoralen + ultraviolet A light (PUVA)
adverse effects: skin ageing, squamous cell cancer (not melanoma)
